This study evaluated the nighttime visibility of three prototypes for an all-weather work zone pavement marking. The prototype markings included retroreflective optics that used beads with higher refractive indices in combination with conventional glass beads. This dual-optic system is intended to provide good visibility in both dry and wet weather conditions. The prototype marking systems were tested alongside two commercially available marking systems (one paint-and-bead system, one wet-reflective removable tape). Thirty study participants ranging in age from 55 to 80 years drove a closed-course that allowed them to view all of the marking types at night under dry conditions, in simulated rain, and on wet pavement following a simulated rain event. Participants were asked to identify the direction of work zone lane shift tapers delineated only by the markings. In thewet-recovery condition, the three prototypes and the reflective tape sustained average detection distances at 60-80% of their dry detection values,and in the continuous rainfall condition sustained average detection distances at 50-70% of dry detection values. In contrast, the average wet-recovery and continuous-rain detection distances for the conventional paint-and-bead benchmark system dropped to 28 percent and 17 percent of the dry detection distance, respectively. In addition, participants failed to detect the conventional paint-and-bead benchmark system in nearly half of the observations in the simulated rain condition.
Abstract